BCAS Vol.31 No.2 2017 China Gears up for Lunar Science By XIN Ling (Staff Reporter) A view of Earth over the far side of the Moon, taken by the Chang'e 5 test vehicle (Chang’e 5-T1) on October 28, 2014. Credit: CAST. 80 Bulletin of the Chinese Academy of Sciences Vol.31 No.2 2017 InFocus hen White House National Security are preserved in the original order, OUYANG told Assistant Zbigniew Brzezinski was visiting BCAS. WBeijing in 1978 for the normalization of Chang’e 5’s landing site near Mons Rümker in US-Sino relations, he presented his Chinese host with a Oceanus Procellarum, which is a large area of lunar special gift: 1 gram of lunar soil enclosed in plexiglass. mare in the northwest region of the Moon, has attracted At that time, few scientists in China knew how to deal world attention. “The Apollo and Luna missions visited with such a sample, so geologist OUYANG Ziyuan was a total of nine sites, all on the nearside quite close to summoned from the CAS Institute of Geochemistry the equator,” said Ian Crawford, a lunar exploration in the remote province of Guizhou to work on it. With specialist from Birkbeck College, University of limited instruments and techniques, his team used half London. “It is important to collect samples from other the gram to complete a series of experiments. They parts of the Moon and Chang'e 5 can make a major found out that it was actually from Apollo 17, the last contribution.” US manned mission to the Moon. According to Crawford, Oceanus Procellarum It is not until the late 1990s that China could start will be an ideal area for sampling because that region thinking about going to the Moon. Named after Chang’e, includes basalts of a wide range of ages, which will allow the mythical Chinese lunar goddess, an ambitious and refinement of the lunar stratigraphy and chronology for well-planned program was unveiled by OUYANG and a better understanding of lunar mantle evolution. his followers. All unmanned technologies are to be Clive Neal, a planetary geologist at the University of tested by 2020, before manned exploration is deployed Notre Dame, USA, was also excited. “Chang’e 5 has an for the ultimate goals of resources utilization and opportunity to bring back some young basaltic material human habitation. The first three probes were launched that we don’t have in existing samples, nor in the lunar successfully in 2007, 2010 and 2013, respectively, and meteorite collection,” said Neal, who had postulated two more are on the way. In November 2017, Chang’e 5 the existence of a new type of lunar basalts based on will bring back two kilograms of soils and make China data from the Chang’e 3 rover. “These samples will be the third country to own their own lunar samples. By important for understanding why volcanism occurred two the end of 2018, Chang’e 4 is going to land on the far billion years ago, and to retrieve the mantle source and side of the Moon for the first time in human history – thermal history of the Moon,” he told BCAS. with the help of a relay satellite to communicate with The solicitation and selection of research proposals the Earth. will begin soon after the samples go through primary classification, OUYANG mentioned. It will be open Sample Return first to domestic scientists and one year later to foreign applicants. A considerable part of the soils will be As the last phase of China’s uncrewed lunar preserved at the National Astronomical Observatories of exploration, Chang’e 5 mainly aims at testing its return China (NAOC) in Beijing. technologies. From taking off from the Moon’s surface to landing on the Earth, its technical readiness seems Explore the Far Side solid. The most challenging part of the mission was rehearsed in 2014: the return capsule bounced and re- Tidally locked to the Earth, the Moon has always entered the Earth’s atmosphere to prevent overheat the same side facing us earthlings when the other side is induced by initial high speed. “invisible”. Studies have shown that it is a very different One highlight of the upcoming two-day round world at the back of the Moon: it is geologically more trip in November will be the robotic sampling of about ancient, and dominated by highlands – unlike the plain two kilograms of lunar soils from the landing spot. landscape that prevails on the near side. The process, which may take a few hours to complete, Though NASA and ESA have well looked into the involves both shoveling and drilling. The soils collected feasibility of going to the lunar far side, the Chinese are by the drill will then be put into a 2m long soft tube so now to make the first trip to the “virgin land”. Following that it can fit into the return capsule while the soil layers the success of Chang’e 3 — China’s first and only Bulletin of the Chinese Academy of Sciences 81 BCAS Vol.31 No.2 2017 China’s unmanned lunar exploration program contains three stages: (I) orbiting missions, (II) landing missions, and (III) sample return missions. Credit: NSSC. landing mission on the Moon by far, Chang’e 4, initially the first stars and the first large-scale structures of the defined as Chang’e 3’s backup, was approved in 2016 to universe formed. perform a similar task on the far side of the planet. “These emissions cannot be observed on Earth Different from Chang’e 3, though, a relay satellite due to ionospheric cut-off, but at the Moon, there is no has to be put up at the Moon-Earth Lagrangian 2 point atmosphere. On the far side, which is shielded from around mid 2018 for the communications between all types of artificial terrestrial radio emissions, there Chang’e 4 and the Earth. The Chang’e 4 probe is less interference from radio noise”, explained Marc (including a lander and a rover) will land six months Klein Wolt from Radboud University Nijmegen, the later in the South Pole-Aitken Basin area, the largest Netherlands, who is in charge of developing the Low and arguably oldest impact basin on the Moon, carrying Frequency Radio Detector (LFRD) on the relay satellite. not only regular payloads like a topography camera There will be two more such detectors on Chang’e and a lunar penetrating radar, but specially developed 4: one on the lander, which is under development at the equipment for the unique science opportunities CAS Institute of Electronics, and a set of two detectors, accessible only on the far side. to ride separately on a pair of microsatellites to orbit the One such example is low-frequency radio Moon and form a radio interferometer. detection. The lunar far side has been regarded as the “The mission will be very difficult,” said Marc, “but “cleanest” place to measure the red-shifted Hydrogen if we succeed, we pave the way for a future large radio 21cm emission line from the early universe. It will facility on or near the Moon.” help scientists peep into “the cosmological dark ages”, CHEN Xuelei from NAOC, who is involved in a period after the Big Bang and before the birth of the the design of the detectors on the microsatellite pair, first stars, which is critical to our understanding of how recognized the scientific uncertainty. “We have a 82 Bulletin of the Chinese Academy of Sciences Vol.31 No.2 2017 InFocus Chang’e 5, schedule for launch end of November 2017. Left: the two-part lander and sample return module. Right: a remote sensing image of the reported landing site near Mons Rümker in Oceanus Procellarum. Credit: CNSA. general idea of what to look at in this wavelength. But solar wind for a much longer time as any point on the frankly, since this has never been done before, we are near side. not sure what we will see.” “The flight instrument is ready tested and The main technical challenge is to reduce the calibrated, and we just delivered the flight model to the radio noise of the satellite or lander itself, which may National Space Science Center (NSSC) in Beijing on severely impact the results of observations, CHEN April 7,” Wieser told BCAS. and Marc admitted. And given the time shortage, they The Lunar Lander Neutrons and Dosimetry (LND) are working around the clock to make prototypes and Experiment, on the other hand, will be equipped on the reduce platform noise. lander to measure the radiation dose which an astronaut would experience on the Moon, said Robert Wimmer- International Collaboration Schweingruber from the University of Kiel in charge of the experiment. Notably, it is the first time that China has rolled out Although there are many models for lunar radiation the red carpet to international collaborators in its lunar exposure, there have never been in situ measurements program. In all, four foreign payloads will be taking on the Moon, he explained. “The constantly present their ride on Chang’e 4. Besides the LFRD, there will galactic cosmic rays interact with the lunar soils to be the Advanced Small Analyzer for Neutrals (ASAN) produce a significant secondary contribution to the from the Swedish Institute of Space Physics in Kiruna, radiation exposure. Therefore, such measurements are the Lunar Lander Neutrons and Dosimetry Experiment important to be made on the surface of the Moon, and (LND) from the University of Kiel, Germany, as well as neutrons are the most dangerous part of this secondary an optical camera from Saudi Arabia.